| 摘要 |
PURPOSE:To attain the line loopback test normally by adding a line loopback circuit while duplicating trunks and switching a system into a standby system if a fault takes place in the trunks so as to restore the line control. CONSTITUTION:A central processing unit 1, a time division switch 2, a line controller 3 and a trunk 4 have duplicated redundancy constitutions and the trunk 4 has a loopback circuit 4a. When the unit 1 discriminates that the system switching of trunk is required at the occurrence of a trunk fault, a system switching order is sent to the controller 3. In order to check the normality of the controller 3 and the trunk 4, when the unit 1 sends a diagnostic order to the standby system of the controller 3, the standby system of the equipment 3 applies its own diagnosis, sets the standby system of the trunk 4 to the diagnostic state, the relay of the circuit 4a is operated to form a loopback.
|
